I suppose that is the only way his comment would make sense. But, I don’t see anyone going “wow how cool, I want to buy one”, I see most readers of this blog going “wow , how cool, I would BUILD one”.

Why work on an 80% AR lower to end up with a rifle that looks like every other AR15, when you can make something like this. That is the remarkable thing about the vid, Something BUILT from hardware tools, not ‘something you could buy’.

I’d have to buy one because I live in a high rise condo therefore don’t have a machine shop. I suppose I could go to a local “maker shop” but I since they mainly consist of hipsters 3D printing and laser cutting hipster stuff I have a feeling making weapons would be frowned upon lol.

IMO this design is much more complicated than it needs to be, and not very robust. It appears that upon firing, the barrel assembly would want to slide forward along the long thin rod (the rod is put under tension). The only thing preventing the rod from separating from the gun is the small set screw that is installed at 0:30. I wouldn’t be brave enough to fire one of these.

I’m not sure I understand the forward forces on the barrel assembly you mention? Gas drag on the barrel after the shot or slug leaves the barrel? If I was concerned about forward forces, I would be worried about thread failure at the front. A .25″ grade 8 bolt will thread fail in excess of 5000 psi with a UNF. I haven’t done the calcs on 1018 cold rolled, but even at 50%? I wouldn’t worry about the set screw. It’s set in a notch and it’s failure mode is in single shear. If it by chance it did fail ahead of the front threads, the rod would pull forward about .5″ and be stopped by the rear brass knob thingie.

And to head off the “blow off my fingers” comments, the barrels are 1045 DOM. The safety factor is X1.5 of the maximum pressure of a .410 shell.

I’ve fired over a hundred rounds and checked for issues, dimensional changes etc. So far the only issue or change is the lighter state of my wallet after buying a hundred rounds.

After ignition, while the shot/slug is still in the barrel, the empty case will want to travel backwards relative to the barrel. So the brass head will push against the circular plate directly behind the barrel, and the barrel assembly will want to move forward relative to the rest of the gun. All of that force would be on the long rod/nut/setscrew, not much cross-sectional area there. I just think that there could be a better way to lock the barrel to the receiver before each shot.

Do you have any other documentation for a closer look? Not worried about it blowing up, but I am impressed that things haven’t loosened up after 100 rounds. Very nice machining BTW.

Interesting. So, if I undo the nut at the business end, and fire a round, the barrel assembly will go flying off in the direction of the target? I’m going to try that and post a video of the results. I love experiments. I’m thinking if the forward forces were anywhere serious enough to stress that rod, the gun would have no recoil. My gut feel is, and I’m not an engineer, is that the mass of the barrel assembly over the short impulse of the aprox 3,5″ that the load has to travel in that very short time span will exert little influence on the barrels. But the proof will be in trying. Right now I’m having a beer and to distracted for math:)

“So, if I undo the nut at the business end, and fire a round, the barrel assembly will go flying off in the direction of the target?”
That’s what I would expect to happen, though it probably wouldn’t go very far. I would do that test with a string just in case some gas escapes out of the back of the barrel. Can’t wait to see the video!

Interesting thread. I think one important thing is being overlooked though. As the gas is expanding behind the shot/slug, the shell also expands, making a gas seal and becoming one with the barrel. The movement of the shell as an opposite reaction to the load being accelerated will move the barrel back. I have close tolerances between the shell and barrel and occasionally I need the extractor (stuck in the slide) to remove shell. It’s my understanding that’s the reason for brass being so widely used for shells. It’s elastic enough to expand, seal and then bounce back for extraction. As I mentioned before, I’m not an engineer, but I still abhor the excess use of materials when not needed. The .25″ rod is more than adequate for the job, mainly to load the barrel assembly in tension, act as a pivot and to function as a guide for the slide stuff on top. I still plan on shooting some video proof. Maybe the owner of this site will publish the results.